Single-Shot Smith-Purcell Longitudinal Bunch Profile Monitor for CLARA with fs resolution

Accurate knowledge of the longitudinal (time) profile of an electron bunch is important in the context of linear colliders, wake-field accelerators and next-generation light sources including X-ray FELs, THz sources and Compton lasers. The profile becomes progressively more difficult to measure as the particle bunches become shorter (fs-scale) or more complex (micro-modulated bunches). Therefore, it is essential to be able to determine the temporal profile with fs resolution, non-destructively and in a single shot. Without this capability it will be very difficult to satisfy the criteria for the next generation light sources (generation of spectrally stable, high intensity and luminosity X-ray pulses) and improve further the performance of wake-field accelerators.
The objectives of this project are:
1/ to design and build the first prototype of a single-shot longitudinal bunch-profile monitor based on coherent Smith-Purcell radiation;
2/ to install it at CLARA facility (Daresbury Laboratory, STFC) and to commission it;
3/ to measure beam profiles with fs resolution and to compare the results with those from other diagnostic devices at CLARA.
4/ to write the research papers, complete and submit the PhD thesis.
The work will be carried out in close collaboration with FMB Oxford and CLARA team. This is essential for reaching objectives and the project success. The design will be based on the results of recent studies and on a conceptual design previously developed. The studies and the conceptual design were supported by STFC (PRD grant and studentship). The monitor development is a part of the JAI research plan.
The operational principles of the conceptual design have been tested at FACET, SLAC (USA) and LUCX, KEK (Japan). It was shown that coherent Smith Purcell radiation (cSPr) is highly polarised while the background radiation is not. This property will be exploited in the design of the monitor, in order to minimise its size and complexity. To reduce time and cost, the construction of the first prototype will use some of the hardware built for the original multi-shot monitor studied at FACET. The prototype will have a single grating, 22 optical channels (11 channels per each polarisation) and beam positioning monitors installed before and after the vacuum chamber. Sampling and analysis of the cSPr signal at 11 frequencies in the frequency range 0.2THz to 1THz will achieve 10fs resolution.
The industrial partner's involvement in the project is crucial to its success. FMB Oxford will bring its expertise in design of diagnostics for particle accelerators and knowledge of specialist techniques which will be required to design and test the monitor. The student will work at FMB facilities, developing the monitor's technical design and testing its components. FMB will supervise, mentor and provide training within the competitive business environment, broadening the student's experience beyond the usual academic framework.